Pressure balanced three-way valve for motion control

ABSTRACT

A switching control valve for use in controlling the motion of a hydraulic component is provided. The valve includes a housing that defines a feed port, an outlet port, a drain port, and a longitudinal opening through the housing. The valve also includes an inlet valve moveably positionable in the longitudinal opening for selectively fluidly connecting the feed port to the outlet port, as well as a drain valve moveably positionable in the longitudinal opening for selectively fluidly connecting the outlet port to the drain port. The valve further includes a valve shaft that is moveably positionable in the longitudinal opening, such as by a solenoid or similar control device, and is operably connected to the inlet valve and the drain valve. The housing, the inlet valve and/or the drain valve are configured to provide permanent fluid communication between the outlet port and the drain port.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a utility patent application claiming priority toU.S. Provisional Patent Application, Ser. No. 60/726,564 filed Nov. 9,2005, entitled PRESSURE BALANCED THREE-WAY VALVE FOR MOTION CONTROL. Thedisclosure of this provisional application No. 60/726,564 is herebyincorporated by reference in its entirety

BACKGROUND

The present invention relates to a switching control valve that controlsthe operation of hydraulic motion systems.

Such hydraulic systems are found in anti-lock braking systems,directional actuators and valve control systems of internal combustionengines. There is an ever-present demand for greater flexibility in thecontrol of such systems.

SUMMARY OF THE INVENTION

In view of the above-identified problems and limitations of the priorart and alternate hydraulically operated devices, the present inventionprovides a single solenoid, pressure-balanced, three-stage, three-wayvalve for controlling the stroke, or the activating force ofhydraulically operated devices.

In one embodiment of the present invention, a switching control valvefor use in controlling the motion of a hydraulic component is provided.The valve includes housing. The housing defines a feed port, an outletport and a drain port. The housing defines longitudinal opening in thehousing. The valve also includes an inlet valve moveably positionable inthe longitudinal opening of the housing for selectively fluidlyconnecting the feed port to the outlet port. The valve also includes adrain valve moveably positionable in the longitudinal opening of thehousing for selectively fluidly connecting the outlet port to the drainport. The valve also includes a valve shaft moveably positionable in thelongitudinal opening of the housing and operably connected to the inletvalve and the drain valve. The valve also includes a solenoid operablyconnected to the valve shaft for moveably positioning the valve shaft inthe longitudinal opening. The housing, the inlet valve and/or the drainvalve are configured to provide permanent fluid communication betweenthe outlet port and the drain port

In another embodiment of the present invention, a device for use incontrolling the motion of a valve in an internal combustion engine isprovided. The device includes a housing that defines a feed port, anoutlet port, a drain port, and a longitudinal opening through thehousing. The device also includes an inlet valve moveably positionablein the longitudinal opening of the housing for selectively fluidlyconnecting the feed port to the outlet port. The device also includes adrain valve moveably positionable in the longitudinal opening of thehousing for selectively fluidly connecting the outlet port to the drainport. The device also includes a valve shaft moveably positionable inthe longitudinal opening of the housing and operably connected to theinlet valve and the drain valve. The device also includes a solenoidoperably connected to the valve shaft for moveably positioning the valveshaft in the longitudinal opening. The housing, the inlet valve and/orthe drain valve are configured to provide permanent fluid communicationbetween the outlet port and the drain port

In yet another embodiment of the present invention, a method forcontrolling the motion of a valve in an internal combustion engine isprovided. The method includes the steps of providing a housing with alongitudinal opening and providing an inlet valve. The method alsoincludes the steps of moveably positioning the inlet valve in thelongitudinal opening of the housing and selectively fluidly connectingthe feed port to the outlet port. The method further includes the stepsof providing a drain valve and moveably positioning the drain valve inthe longitudinal opening of the housing. The method includes the stepsof permanently fluidly connecting the outlet port to the drain port andproviding a valve shaft. The method includes the steps of moveablypositioning the valve shaft in the longitudinal opening of the housingoperably connecting the valve shaft to the inlet valve and the drainvalve and providing a solenoid. The method includes the steps ofoperably connecting the solenoid to the valve shaft and moveablypositioning the valve shaft in the longitudinal opening.

BRIEF DESCRIPTION OF THE DRAWINGS

Features of the present invention will become apparent to those skilledin the art from the following description with reference to thedrawings, in which:

FIG. 1 is a cross-sectional view along the longitudinal axis of athree-way valve according to an embodiment of the invention, andincluding enlarged views at various locations of the valve;

FIG. 2 is a cross-sectional view of the valve of FIG. 1 integrated intothe head of a hydraulic device;

FIG. 3 includes a series of cross-sectional schematic views of the fluidflow through the valve of FIG. 1 at different stages of operation of thevalve;

FIG. 4 is a cross-sectional view of valve of FIG. 1 integrated into amodified head of a hydraulic device similar to that shown in FIG. 2;

FIG. 5 includes side and top cross-sectional views of a ball valvecontrolled by a three-way valve according to another embodiment of theinvention;

FIG. 6 is a cross-sectional view of a three-way valve according toanother embodiment of the invention;

FIG. 7 is a cross-sectional view along the longitudinal axis of athree-way valve configured for use for controlling ABS systems accordingto another embodiment of the invention, and including enlarged views atvarious locations of the valve; and

FIG. 8 is a flowchart detailing the basic steps of the valve accordingthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and described in the following written specification. It isunderstood that no limitation to the scope of the invention is therebyintended. It is further understood that the present invention includesany alterations and modifications to the illustrated embodiments andincludes further applications of the principles of the invention aswould normally occur to one skilled in the art to which this inventionpertains.

In an embodiment of the invention, a valve V shown in FIG. 1 includes asolenoid stator 3 which may be de-energized or energized at twodifferent current levels. A valve housing 13 houses two pressurebalanced valves—an inlet valve 9 and a drain valve 15. The valves may bepoppet valves. The inlet valve 9 is pressure balanced in both its openand its closed positions, regardless of pressures in the outside cavity21 or in the annulus 23 behind the inlet valve seat 13 a (see View C ofFIG. 1). To achieve this pressure balancing feature, a floating sleeve 6is used which has an inner diameter SLEEVE_d that is the same as thebore diameter HOLE_dia, and which is also the same as the sealingdiameter at the contact between the inlet valve's sealing surface 9 aand the valve seat 13 a. To improve the sealing at the end surface ofthe floating sleeve 6 and to avoid excessive side load due tomanufacturing inaccuracies, a specially formed elastic or elastomericseal 5 is located at the left end of the sleeve, as shown in the detailView B. The sealing force of the floating sleeve 6 on the seal 5 can becontrolled by adjusting the contact diameter C_d of the sleeve relativeto its outer diameter, the wall thickness of the sleeve at the contactsurface, the high (inlet) pressure of the fluid within the valve V andthe spring force exerted by the inlet spring 7.

Outside the inlet valve seat 13 a and the drain valve seat 13 b (View Aof FIG. 1) are two cavities 21, 22, respectively, defined within thevalve housing 13. The inlet cavity 21 is in fluid communication with ahigh pressure feed rail 31 (FIG. 2) through feed ports 18. The draincavity 22 is in fluid communication with a drain rail 35 (FIG. 2). Theports 18, 19 and 20 may be preferably uniformly disposed around thecircumference of the valve body, surrounded by the corresponding rail31, 35.

In the illustrated embodiment, the floating sleeve 6, inlet spring 7,stroke limiting shim 8 (View D of FIG. 1) on which the spring 7 acts,inlet spacer 11 that bears on a gap shim 12 to maintain spacing betweenthe inlet and drain valves, the inlet valve 9, the middle spring 10, thedrain spacer 14 and drain valve 15, and the drain spring 16, are allpreferably assembled on one side of the stroke limiting shoulder 17 a ofthe valve shaft 17 (View B of FIG. 1). On the other side of thisshoulder 17 a are the stator spacer 4, the stator 3, armature spacer 25and armature 2.

The inlet valve 9 and drain valve 15 are slidably disposed within thevalve housing 13 and about the inlet and drain spacers 11, 14,respectively. The stroke limiting shim 8 can also slide on the inletspacer 11, but is limited to movement together with the inlet valve 9due to the inlet spring 7. The armature 2, armature spacer 25, inletspacer 11, gap shim 12 and drain spacer 14 are all preferably fixed orattached to the valve shaft 17, such as by nut and bolt arrangement atthe ends of the valve shaft 17.

The annulus 23 of the inlet valve 9 is in fluid communication with theactivating plunger 33 (FIG. 2) through the active outlet ports 19 andoutlet rail 33 a. The outlet ports are preferably in fluid communicationwith the drain ports 20 through flutes 26 (Section H-H of FIG. 1)located on the external surface of the valve housing 13. A clamping nut1 is used to clamp the entire valve cartridge within the housing of theexternal rails 31, 33 a, 35, as depicted in FIG. 2. This externalhousing can also contain a high pressure check valve 32 between the feedrail 31 and the outlet rail 33 a and a drain check valve 34 between thedrain rail 35 and the outlet rail 33 a.

Another embodiment of the present invention is in the form of a valvesimilar to that of FIGS. 1 and 2 but further including motion sensorsfor each engine valve. This embodiment is shown in phantom in FIG. 2.Motion sensors 67 (shown in phantom) may be connected to a controllingcomputer 69 (shown in phantom) to provide immediate feedback to thecontrolling computer 69 with respect to movement of the valve. Themotion sensors 67 may permit accounting for changes in valve responsedue to a variety of factors including variable viscosity that may be theresult of the temperature change. The motion sensors 67 may be anysensor capable of providing signals to the computer 69. Such sensors maybe for example a proximity or Hall effect sensor that generates a pulsewhenever the sensor comes in close proximity to an object. Othersensors, for example, incremental optical encoders and laserinterferometers, may also be used.

The manner of operation of the valve V of FIGS. 1-2 is depicted in thesequential views of FIG. 3. In the illustrated embodiment, the valve Vcontrols engine inlet and/or exhaust valve(s) through the activatingplunger 33. When the solenoid 3 is de-energized, the inlet spring 7holds the inlet valve 9 on the inlet seat 13 a, sealing the highpressure feed I from the activating plunger 33. At the same time, themiddle spring 10 forces the valve shaft 17 away from the solenoid stator3 until it reaches the stroke limiting shim 8. It can be appreciatedthat the thickness of the shim can be adjusted to vary the stroke of thevalve shaft. At this point, the drain valve 15 is pushed against the gapshim 12 by the drain spring 16, which results in the drain valve sealingsurface 15 a moving away from the drain seat 13 b. This action thusconnects the activating plunger 33 to the drain rail 35 and drain flow Dto prevent movement of the plunger, and ultimately to keep the enginevalve closed.

When the solenoid stator 3 is energized at a high level current, thearmature 2 pulls the valve shaft 17 against the pre-load of the middlespring 10, as depicted at Step 2 in FIG. 3. As the valve shafttranslates, the drain valve sealing surface 15 a contacts the seat 13 b.At the high level current, the solenoid is capable of overcoming thepre-load of the drain spring 16 and middle spring 10, so the shaftcontinues to translate, compressing the drain spring 16 and providingsufficient sealing force towards the drain cavity 22. The gap betweenthe end surfaces of the inlet valve 9 and the drain valve 15 is greaterthan the thickness of the gap shim 12. Thus, when both valves are seatedfurther motion of the valve shaft 17 initially compresses the middlespring 10 until the gap shim 12 contacts the end of the inlet valve 9.The small air gap (Dimension “a”+Dimension b) between the stator 3 andarmature 2 allows the magnetic force in the solenoid to increase to ahigher level sufficient so that the valve shaft 17 will force the inletvalve 9 from its seat 13 a against the force of the inlet spring 7.Apart from possible inertia forces produced by the acceleration anddeceleration of the valve components, the magnetic force of the solenoidis working against the combined force of the inlet spring 7 and drainspring 17. Movement of valve shaft 17 is limited when the strokelimiting shoulder 17 a contacts the solenoid spacer 4.

During the time that the inlet valve 9 is open, the high pressure inletfluid I can flow from the feed rail 31 to the activating plunger 33.When the activating plunger is part of an engine valve system, theplunger generates hydraulic force to open the engine valve against thebiasing force tending to keep that valve closed. Typically, the maximumstroke of the activating plunger 33 is mechanically and hydraulicallylimited. Apart from this maximum stroke limit, other parameters such aspressure, temperature, media viscosity, fluid volume, flow areas,plunger diameter and the like—the time that the inlet valve 9 is opendetermines the stroke of the activating plunger 33, and ultimately thestroke of the engine valve driven by the plunger.

When the desired open time of the inlet valve 9 (and ultimately theengine valve stroke) has been reached, the current in the solenoid isdropped to a medium level, as depicted in Steps 3-4 of FIG. 3. At thislevel, the magnetic force generated by the solenoid is no longer enoughto hold the inlet valve 9 in the open position (Step 2) against thecombined force of the springs 7 and 16. Thus, the valve shaft 17 movesback until the inlet valve 9 is seated. At this point, the spring forceof the inlet spring 7 is taken up by the seat 13 a to that the inletspring is no longer working against the solenoid magnetic force. Thedecreased magnetic force is still greater than the force of the drainspring 16 and middle spring 10, so the valve shaft 17 will stay in themiddle position, causing both valves 9 and 15 to stay closed. (Step 3 inFIG. 3). In this position, the fluid is neutral N or trapped over theactivating plunger 33, which for an engine will cause the engine valveto stay in its open position. The thickness of the gap shim 12 issmaller than the distance between the ends of the seated inlet and drainvalves 9 and 15 to give some free play.

The characteristics of the solenoid magnetic force are necessarilyshaped in relation to the spring forces it must work against. Using anenergy efficient solenoid, the magnetic force vs. the armature motionfrom the initial maximum air gap is too progressive. In order to be ableto release the armature from the minimum air gap, the holding currentwould normally be dropped significantly. However, the current value thatcould hold the armature in the middle position still holds the armatureat the minimum air gap position. On the other hand, a sufficiently lowreleasing current is not enough to hold the armature in position at agreater air gap, such as at the middle position, so the valve shaft 17may move to an unintended position where the drain valve 15 will beopen. To avoid this discrepancy, the armature 2 is conically shaped sothat as the armature approaches the stator 3 the air gap Dimension “a”will decrease but the air gap Dimension “b” will increase. The forcecharacteristic will be less progressive or flatter. This flatnessdepends on the cone angle ALPHA and the initial values of the air gapDimensions a, b.

Closing the engine valve is depicted in Steps 5-7 of FIG. 3. In order toclose the valve, the solenoid current is dropped to zero—i.e., thesolenoid 3 is de-energized. In this case, the middle spring 10 and drainspring 16 both operate to force the valve shaft 17 farther from thestator 3 until the drain valve 15 contacts the gap shim 12. At thispoint the drain valve 15 leaves the seat 13 b and moves together withthe valve shaft 17, which is still forced to move by the middle spring10. This motion stops when the shoulder 17 b of the valve shaft 17contacts the stroke limiting shim 8 (View D of FIG. 1). At thisposition, the drain valve 15 has already opened to the drain rail 35,the active plunger 35 is connected to the drain flow D, and the enginevalve begins closing.

To avoid unintended forces caused by built-up pressure, all internalcavities are connected to each other and to the drain rail 35. Thisfluid communication is provided by the flutes 15 b inside the drainvalve 15, the flats 12 a on the gap shim 12, as well as additional holesand chamfers located where necessary.

When the solenoid current is dropped from the high current level to themedium level, after the inlet valve 9 is closed and the high pressuresupply is cut off, the activating plunger 33 and engine valves are stillmoving due to their own inertia. This generates depression or cavitationin the trapped volume. To avoid this problem, a drain check valve 34 isintroduced between the drain rail 35 and the outlet rail 33 a. Thischeck valve automatically opens when the pressure difference at thecheck valve is sufficient to overcome the check valve spring, therebyre-filling the activating plunger volume from the drain rail. In orderto accomplish this feature, the drain pressure is preferably on theorder of 2 MPa.

Another issue is the impact force caused by the high speed at which anactivated engine-valve closed onto its seat. If the solenoid 3 isenergized at the medium current level right before the engine valvereaches its seat, the media will be trapped again. The inertia of themoving parts will generate high pressure above the activating plunger33. On the one hand, this high pressure naturally slows down the movingparts. On the other hand, because the pressure is higher than the highpressure system (typically at 25-30 MPa), a high pressure check valve 32is introduced between the outlet rail 33 a and the feed rail 31. Thischeck valve allows the activating plunger—by means of the highpressure—to recuperate some part of the kinetic energy of the movingengine valve components.

One modification of the invention addresses the risk of a faulty valveoperation, such as might occur in an engine valve. Thus, as shown inFIG. 4, a plunger 51 is loaded with a spring 52 and a coaxial guidedneedle 53. In the basic position, the plunger 51 and needle 53 do notexert any force on the drain check valve 34. When a separate three-wayvalve (not shown) directs pressurized media through the passage 54 tothe plunger 51, the plunger 51 pushes the needle 53 which opens thedrain check valve 34. Thus, in this condition the high pressure mediaflows to the drain without forcing the activating plunger 33 to move.The plunger 51 is pressurized during the time that the engine piston iscloses to the cylinder head.

In a further embodiment of the invention, a modified engine valve V″,shown in the two views of FIG. 5, is mounted on the cylinder head 70 ofan engine. The modified engine valve V″ is controlled by valve V ofFIGS. 1 and 2. A ceramic or ceramic-coated spherical ball valve 71 isdisposed between a lower seat 72 and an upper seat 81. The ball valve 71is rotated by a threaded shaft 73, forced to revolve without any axialmotion by means of a matching threaded sleeve 76. The sleeve 76 movesaxially, but does not rotate. The axial movement of the sleeve 76 isgenerated in the opening direction by a specially shaped activatingplunger 77, in lieu of the plunger 33 in the prior embodiments. A spring82 or a pneumatic/hydraulic plunger (not shown) works against theplunger 77. A plunger guide 79 is provided within the hydraulic cylinder80 to restrict any rotation of the activating plunger 77. The positionof the plunger guide 79 may be adjusted to obtain the proper flow areafor an idle condition.

The restriction of any rotation of both the plunger 77 and the threadedsleeve 76 is carried out with rib-sleeve connections 80 a-77 b and 77a-73 b between adjacent parts. The axial motion of the threaded shaft 73is stopped by the ball valve 71 and the spring retainer 74. The shaft 73rotates the ball valve 71 through the connection 71 a-73 a. To obtainproper sealing force against the peak cylinder pressure, the upper seat81 is compressed mechanically, hydraulically, electrically orpneumatically (not shown). The pressurized media, controlled by a valveV′, is fed to the plunger 77 through the feed ports 83 and 84. Theleakage, after lubricating the shaft 73 and the sleeve 76, drains backto the cylinder block through a hole 75. The ball valve of thisembodiment provides better hydraulic/geometric flow area ratio and lesswet wall area than prior valve systems. Using a bar instead of a ballmay increase flow area but may also produce flow sealing problems.

To get proper sealing force against the peak cylinder pressure, theupper seat 81 is to be pressed down mechanically, hydraulically,electrically or pneumatically (these are not shown in the figure). Inorder, to achieve smaller size (or lower operating pressure), lessenergy consumption, less wear and shorter response time, electric (e.g.with piezo crystal) or hydraulic load is desirable. In this case duringmoving the ball valve 71, the down force can be minimized.

Referring now to FIG. 6 another embodiment of the invention is shown asa three-way valve V′. The valve V′ is similar to valve V of FIGS. 1 and2, except that a middle spring 108, instead of the inlet valve 9 and thegap shim 12 of the valve V is placed between the inlet valve 102 anddrain valve 103. Optionally, spacers, for example two limiting discs 104and the spring retainer 107 may be positioned at the external end of thedrain valve 103 to assist in controlling free play of the valve shaft105 between the two valves at their closed position. In this embodiment,the armature 106 has more traditional shape. The operation of thisversion is the same as valve V of FIGS. 1 and 2.

The three-way valve V′ depicted in FIG. 6 includes a solenoid stator 113that has a de-energized state as well as two different holding currentstates. The stator 113 is supported on a valve housing 101. The housingdefines an inlet valve 102 and a drain valve 103 situated at oppositeends of a bore 117 passing through the housing. The housing furtherdefines an inlet cavity 122 and a drain cavity 123 at opposite ends ofthe bore 117. The inlet cavity 122 communicates with a feed port 118through which hydraulic fluid is supplied, while the drain cavity 123communicates with a drain port 119 to discharge fluid from the valve.

The inlet and drain valves 102, 103 are held in position or forced tomove by means of a valve shaft 105 that passes concentrically throughthe valves. The armature 106 of the solenoid 113 is attached at one endof the valve shaft 105, while a spring retainer 107 is attached at theopposite end of the shaft. A shoulder 105 a is formed on the shaft 105between the inlet valve 102 and the drain valve 103 to maintain providemeans for opening the inlet valve 102 or the drain valve 103 independentof the other under certain operating conditions of the three-way valveV′.

The valve V′ includes three springs concentrically disposed around theshaft 105. An inlet spring 109 acts against the inlet valve 102 to urgethe valve to the closed position shown in FIG. 6. A middle spring 108 isdisposed between the inlet and drain valves 102, 103 to convey forcesbetween the two valves to open the drain valve 103 under certainconditions. The third spring is a drain spring 110 that is situatedwithin a cavity 103 a in the drain valve. The spring retainer 107attached to the valve shaft 107 traps the drain spring 110 within thecavity. An optional stop 104 can take over part of the task of theshoulder 105 a, making the drain valve 103 opening adjustable. In thiscase there will not be any contact between the shoulder 105 a and drainvalve 103.

A gliding spring retainer 120 is provided in order to ensure pressurebalance at the inlet valve 102 throughout the entire operating range ofthe valve and to seal the high pressure inlet side from the low pressuredrain side of the bore 117. The gliding retainer 120 is disposed withinthe inlet cavity 122 and seats on an elastomeric gasket 121. The inletspring 109 bears against the retainer 120, which in turn bears againstthe gasket 121 to maintain the fluid seal. A gasket carrier 111 andsolenoid spacer 112 may be provided to support the gasket 121 and thesolenoid stator 113 on the valve housing 101.

A hydraulic system body 114 may support the valve housing 101 and helpdefine the drain cavity 123. The drain cavity communicates with apassage 123 a that feeds an active outlet 124 through a check valve 116.Similarly, the inlet cavity 122 communicates with a passage 122 a thatfeeds the active outlet 124 through a second check valve 115. Flowthrough the active outlet is two way so that the check valve 116prevents return flow from the outlet 124 but permits flow into theoutlet. Likewise, the check valve 115 prevents inlet flow into theactive outlet 124 while permitting return flow from the outlet back intothe inlet cavity 122.

The valves include poppet surfaces that close the valve against acorresponding surface of the inlet or drain cavities. Thus, the inletvalve 102 includes a poppet surface 102 b that closes the inlet cavity22 to the passage 24 a that feeds the active outlet 124. Drain valve 103includes a poppet surface 103 b that closes the drain cavity 123 to thepassage 124 b that also communicates with the active outlet 124. Theactive outlet 124 is connected to an active hydraulic system thatbenefits from the three-stage capabilities of the valve V′ of FIG. 6.For instance, the active outlet 124 may be connected to a hydraulicallyoperated inlet/exhaust valve/s in a camless engine.

One form of operation of the valve V′ is depicted in the schematics ofFIG. 3. In this embodiment, the valve V′ may control an air controlvalve in a camless engine. When the stator is de-energized, the inletflow I is closed from the active outlet. Instead the active outletprovides drain flow D so that the engine valve remains closed. When ahigh current level is applied to the solenoid 113, the inlet and drainvalves are pulled upward until the inlet valve is open to the activeoutlet and the drain valve is closed. In this condition inlet fluid flowI may occur through the inlet and the active outlet to begin opening theengine valve. In the next condition, the engine valve has opened and thefluid flow works against the drain valve and its check valve so that theactive outlet is connected to the drain fluid flow D.

At this point, the solenoid is reduced to a lower holding current sothat both valves close. In this condition neither the inlet nor thedrain is in communication with the active outlet, which instead is heldneutral N. In the next stage, the solenoid is de-energized to beginclosing the engine valve. Once the engine valve is closed, the drainvalve closes, the inlet valve opens and the active outlet is coupled tothe inlet fluid flow I.

According to yet another embodiment of the invention and referring nowto FIG. 7, a three-way valve V′″ is shown. The valve V′″ is a modifiedversion of the valve V of FIGS. 1 and 2. The three-way valve V′″ may beused on for example an antilock (ABS) brake system. In a brake system onthe one hand the force—pressure—is to be controlled, not the stroke, onthe other hand there must be a constant hydraulic connection between themaster—and the slave cylinder, as a default. For this purpose, in casethe solenoid (not shown) is deenergized, the inlet valve 205 is open andthe return valve 211 is closed, making possible the fluid-communicationfrom the master cylinder through the inlet 215 of the control block 201;the inlet holes 216 of valve housing 206; between the inlet valve'ssealing shoulder 205 a and its seat 206 a in the valve housing 206; theoutlet holes 217 of valve housing 206; and the outlet 218 of controlblock 201 to the slave cylinder. When the wheel-deceleration exceeds thelimit, the solenoid (not shown) is energized on medium level and bymeans of the armature 214 pulls the valve shaft 207, until the middlestop 208 contacts the return valve 211, which stops the motion, based onthe—higher than magnetic force—preload of the return spring 212. Duringthis motion, first the inlet valve 205 moves with the valve shaft 207,until its sealing shoulder 205 a contacts the inlet seat 206 b. Theclosed inlet disconnects the slave cylinder from the master cylinder.The further motion till the stop is achieved by means of the gap betweenthe middle stop 208 and the return valve 211.

At this short stroke the valve shaft 207 moves relative to the inletvalve 205 compressing the inlet spring 204 and middle spring 210. Incase the wheel deceleration is still higher than the limit, the solenoidis energized on the high level, when the magnetic force overcomes thesum of the preload of the return spring 212 and inlet spring 204. Thusthe return valve's sealing shoulder 211 a leaves its seat 206 b in thevalve housing 206 and the fluid will be able to flow through the outletholes 219 of valve housing 206; the return holes 220 of valve housing206; and the return outlet 221 of control block 201 to the returningpump, which delivers the fluid back to the brake system.

Both the inlet valve 205 and return valve 211 are pressure balanced inopen and closed position, as this was explained earlier. The pressurebalance of the inlet valve 205 is independent of the side of the seatthat the pressure is acting on, because the inlet valve 205 is moving ina floating sleeve 203, which rests on an elastic gasket 202, similar tothe previous example. Extra sealing force can be obtained fromadditional spring, placed either inside the valve shaft 207 at the inletend, or—using different geometry—between the valve housing 206 and thefloating sleeve 203. The whole unit is retained in the control block 201by the retainer 213 and the middle stop 208 is held in position by theretaining ring 209. The maximum opening is determined by the floatingsleeve/valve shaft contact 203/207 and the other extreme—at max energylevel—is determined by the return valve/retainer contact 211/213.

According to the present invention and referring now to FIG. 8, anotherembodiment of the present invention is shown as a method 300 forcontrolling the motion of a valve in an internal combustion engine isprovided. The method includes the steps 310 and 312 of providing ahousing with a longitudinal opening and providing an inlet valve. Themethod also includes the steps 314 and 316 of moveably positioning theinlet valve in the longitudinal opening of the housing and selectivelyfluidly connecting the feed port to the outlet port. The method furtherincludes the steps 318 and 320 of providing a drain valve and moveablypositioning the drain valve in the longitudinal opening of the housing.The method includes the steps 322 and 324 of permanently fluidlyconnecting the outlet port to the drain port and providing a valveshaft. The method includes the steps 326 328 and 330 of moveablypositioning the valve shaft in the longitudinal opening of the housing,operably connecting the valve shaft to the inlet valve and the drainvalve and providing a solenoid. The method also includes the steps 332and 334 of operably connecting the solenoid to the valve shaft andmoveably positioning the valve shaft in the longitudinal opening.

Variations and modifications of the present invention are possible,given the above description. However, all variations and modificationswhich are obvious to those skilled in the art to which the presentinvention pertains are considered to be within the scope of theprotection granted by this Letters Patent.

1. A switching control valve for use in a controlling the motion of ahydraulic component, said valve comprising: a housing defining a feedport, an outlet port and a drain, said housing defining longitudinalopening therein; an inlet valve moveably positionable in thelongitudinal opening of said housing for selectively fluidly connectingthe feed port to the outlet port; a drain valve moveably positionable inthe longitudinal opening of said housing for selectively fluidlyconnecting the outlet port to the drain; a valve shaft moveablypositionable in the longitudinal opening of said housing and operablyconnected to said inlet valve and said drain valve; and a solenoidoperably connected to the valve shaft for moveably positioning saidvalve shaft in the longitudinal opening, wherein the housing isconfigured to provide permanent fluid communication between the outletport and the drain.
 2. The switching control valve of claim 1, whereinat least one of said inlet valve and said drain valve comprises a poppetvalve.
 3. The switching control valve of claim 1, wherein said solenoidcomprises a member with three distinct positions, each of the threepositions corresponding to a unique current level.
 4. The switchingcontrol valve of claim 3, wherein the unique current levels include a nocurrent level, a low current level and a high current lever.
 5. Theswitching control valve of claim 4, wherein when said valve shaft is atone of the three distinct positions of the valve shaft the feed port isclosed and the drain is open.
 6. The switching control valve of claim 4,wherein the distinct position of the valve shaft when the feed port isclosed and the drain is open corresponds to a no current level.
 7. Theswitching control valve of claim 4, wherein the distinct position of thevalve shaft when the feed port is open and the drain is closedcorresponds to a high current level.
 8. The switching control valve ofclaim 4, wherein the distinct position of said valve shaft when the feedport is closed and the drain is closed corresponds to a low currentlevel.
 9. The switching control valve of claim 4, wherein when saidvalve shaft is at one of the three distinct positions of said valveshaft the feed port is closed and the drain is closed.
 10. The switchingcontrol valve of claim 4, wherein when said valve shaft is at one of thethree distinct positions of the valve shaft the feed port is open andthe drain is closed.
 11. The switching control valve of claim 1, furthercomprising a first check valve.
 12. The switching control valve of claim11, wherein said first check valve is positioned in said switchingcontrol valve so that the check valve permits flow from the drain portto the outlet.
 13. The switching control valve of claim 11, furthercomprising a second check valve.
 14. The switching control valve ofclaim 13, wherein said second check valve is positioned in saidswitching control valve so that said second check valve permits flowfrom the outlet to the feed port.
 15. The switching control valve ofclaim 1, further comprising an activation plunger fluidly connected tothe outlet port.
 16. The switching control valve of claim 1, wherein:the longitudinal opening of said housing defines a cylindrical bore; andsaid inlet valve and said drain valve are slidably positionable in thebore.
 17. The switching control valve of claim 1, wherein said housingdefines a cavity for providing fluid communication between the outletport and the drain.
 18. The switching control valve of claim 1,whereinsaid solenoid includes a conically shaped armature.
 19. The switchingcontrol valve of claim 1, further comprising a spherical ball valve asan engine valve.